The original Glock was designed for the 9x19, a tapered round. Glock 9x19 chambers are nice and tight. The tapered cartridge feeds very well.
When they had to adapt their pistol to US cartridges, they had to deal with straight wall cartridges such as 40 S&W, 10mm, 45ACP. To assure reliability they went nuts with the chambers making them loose and without the support we were used to. Putting a round in the barrel of a G21 and looking at the bottom reveals the problem, no support. The 45 is their worst. If it was not for the low pressures of the 45, every single round would be a KB.
I cannot understand why the US manufacturers keep designing straight wall semi auto cartridges when a little taper can make them feed so much better and can use a tight chamber.

I'm not quite sure what to make of this. It's a pretty poor excuse for Glock's shoddy design. You are entirely correct about the 45 ACP being a low pressure round and being the only reason they didn't have KBs, with all the Glock 45s.

The 10mm that you refer to, is actually a European design, by Norma.

The 45 ACP is over 100 years old. It shouldn't be a surprise to the Europeans, about straight wall pistol cases. The Glock 21 is the new kid on the block. Glock is the only gun that I've ever seen a bulged 45 ACP case from.